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Graphene Membranes Make Clean Water

January 16th, 2014 | Posted by spoadmin in Graphene - (0 Comments)

Researchers from MIT, the Oak Ridge National Laboratory (ORNL) and the King Fahd University of Petroleum and Minerals, and others published their most recent advance in the journal ACS Nano (“Selective Molecular Transport through Intrinsic Defects in a Single Layer of CVD Graphene”). Basically they made relatively large membranes from single sheets of graphene grown by chemical vapour deposition, and found that the material generated usable defects, or holes in the graphene sheets.  Source:

http://investorintel.com/graphite-graphene-intel/graphene-membranes-make-clean-water/

Rice, Moscow State universities collaborate on solution to toxic groundwater woes

HOUSTON – (Jan. 8, 2013) – Graphene oxide has a remarkable ability to quickly remove radioactive material from contaminated water, researchers at Rice University and Lomonosov Moscow State University have found.

A collaborative effort by the Rice lab of chemist James Tour and the Moscow lab of chemist Stepan Kalmykov determined that microscopic, atom-thick flakes of graphene oxide bind quickly to natural and human-made radionuclides and condense them into solids. The flakes are soluble in liquids and easily produced in bulk.

The experimental results were reported in the Royal Society of Chemistry journal Physical Chemistry Chemical Physics.

The discovery, Tour said, could be a boon in the cleanup of contaminated sites like the Fukushima nuclear plants damaged by the 2011 earthquake and tsunami. It could also cut the cost of hydraulic fracturing (“fracking”) for oil and gas recovery and help reboot American mining of rare earth metals, he said.

Graphene oxide’s large surface area defines its capacity to adsorb toxins, Kalmykov said. “So the high retention properties are not surprising to us,” he said. “What is astonishing is the very fast kinetics of sorption, which is key.”

Read the abstract at http://pubs.rsc.org/en/Content/ArticleLanding/2013/CP/C2CP44593J

See more at: http://news.rice.edu/2013/01/08/another-tiny-miracle-graphene-oxide-soaks-up-radioactive-waste/#sthash.2sM8kKjQ.dpuf

Research collaboration between Russian and US chemists has discovered a new use for graphene oxide flakes—the clean-up of radionuclide contaminatedwater[1][2].  Radioactive elements are harmful even in small concentrations, making any remediation of radioactive materials in water a slow process simply for the facts that very few radioactive particles may come in contact with reactants that have relatively little surface area for reaction.  Graphene Oxide flakes inherently have large surface areas and are readily soluble in liquids.  In addition to their large relative surface area, these nanothin particles have very fast sorption kinetics.  These nanoflakes react with radioactive material including rare earth elements, plutonium, and uranium in liquids, attracting them to their surface and creating a precipitate in the liquid that is easily filtered[3].

The graphene oxide flakes are easily manufactured and display better sorption kinetics than bentonite clays or activated carbon filters used in conventional radioactive contaminated water cleanup.  While the graphene does not eliminate the radioactive wastes, it concentrates the waste into a solid making it much easier to deal with.  Graphene oxide is combustible, burning rapidly.  This property allows the concentrated radioactive materials to be concentrated into dry solids that can then be repurposed and recycled for fuel or can be mined for their rare earth minerals in the case of water contaminated with radioactive actinides or lanthanides.

Graphene Oxide is manufactured through a simple chemical reduction-oxidation (RedOx) method that requires mixing crystalline graphite with sodium nitrate, sulfuric acid, and potassium permanganate[4].  The formation of the thin films to create flakes is done by either chemical reduction with hydrazine, or bacterial synthesis; the latter being a “green” method free of additional chemicals.

Figure 1: Left: Graphene oxide flakes dissolved in water. Right: Graphene oxide flakes clumping with radioactive materials in solution (Source: Romanchuk, Anna Yu 2013)
Source:  http://nice.asu.edu/nano/using-graphene-decontaminate-radioactive-fluids